10.1021/ja026211g.s001
Tomoyuki Akutagawa
Tomoyuki
Akutagawa
Tatsuo Hasegawa
Tatsuo
Hasegawa
Takayoshi Nakamura
Takayoshi
Nakamura
Tamotsu Inabe
Tamotsu
Inabe
Supramolecular Cation Assemblies of Hydrogen-Bonded
(NH<sub>4</sub><sup>+</sup>/NH<sub>2</sub>NH<sub>3</sub><sup>+</sup>)(Crown Ether) in [Ni(dmit)<sub>2</sub>]-Based Molecular
Conductors and Magnets
American Chemical Society
2002
crown ethers
oxygen atoms
supramolecular cations
NH 4
CH 3 CN
Supramolecular Cation Assemblies
2002-06-29 00:00:00
Journal contribution
https://acs.figshare.com/articles/journal_contribution/Supramolecular_Cation_Assemblies_of_Hydrogen-Bonded_NH_sub_4_sub_sup_sup_NH_sub_2_sub_NH_sub_3_sub_sup_sup_Crown_Ether_in_Ni_dmit_sub_2_sub_-Based_Molecular_Conductors_and_Magnets/3643284
Hydrogen-bonded supramolecular cation assemblies of (NH<sub>4</sub><sup>+</sup>/NH<sub>2</sub>−NH<sub>3</sub><sup>+</sup>)(crown ether), where
the crown ether is [12]crown-4, [15]crown-5, or [18]crown-6, were incorporated into electrically conducting
[Ni(dmit)<sub>2</sub>] salts (dmit<sup>2-</sup> = 2-thioxo-1,3-dithiole-4,5-dithiolate). (NH<sub>4</sub><sup>+</sup>)([12]crown-4)[Ni(dmit)<sub>2</sub>]<sub>3</sub>(CH<sub>3</sub>CN)<sub>2</sub> had
a pyramidal shape, while ionic channels were observed in (NH<sub>4</sub><sup>+</sup>)<sub>0.88</sub>([15]crown-5)[Ni(dmit)<sub>2</sub>]<sub>2</sub> and (NH<sub>4</sub><sup>+</sup>)<sub>0.70</sub>([18]crown-6)[Ni(dmit)<sub>2</sub>]<sub>2</sub>. Both (NH<sub>4</sub><sup>+</sup>)<sub>0.88</sub>([15]crown-5) and (NH<sub>4</sub><sup>+</sup>)<sub>0.70</sub>([18]crown-6) contained regularly spaced
[Ni(dmit)<sub>2</sub>] stacks formed by N−H···O hydrogen bonding between the oxygen atoms in crown ethers and
the NH<sub>4</sub><sup>+</sup> ion. NH<sub>4</sub><sup>+</sup> occurred nonstoichiometrically; there were vacant ionic sites in the ionic channels. The
ionic radius of NH<sub>4</sub><sup>+</sup> is larger than the cavity radius of [15]crown-5 and [18]crown-6. Therefore, NH<sub>4</sub><sup>+</sup> ions
could not pass through the cavity and were distributed randomly in the ionic channels. The static disorder
caused the conduction electrons to be randomly localized to the [Ni(dmit)<sub>2</sub>] stacks. Hydrazinium (NH<sub>2</sub>−NH<sub>3</sub><sup>+</sup>) formed the supramolecular cations in (NH<sub>2</sub>−NH<sub>3</sub><sup>+</sup>)([12]crown-4)<sub>2</sub>[Ni(dmit)<sub>2</sub>]<sub>4</sub> and (NH<sub>2</sub>−NH<sub>3</sub><sup>+</sup>)<sub>2</sub>([15]crown-5)<sub>3</sub>[Ni(dmit)<sub>2</sub>]<sub>6</sub>, possessing a sandwich and club-sandwich structure, respectively. To the best of our
knowledge, these represent the first hydrazinium−crown ether assemblies to be identified in the solid. In
the supramolecular cations, hydrogen bonding was detected between the ammonium or the amino protons
of NH<sub>2</sub>−NH<sub>3</sub><sup>+</sup> and the oxygen atoms of crown ethers. The sandwich-type cations coexisted with the [Ni(dmit)<sub>2</sub>] dimer stacks. Although the assemblies were typically semiconducting, ferromagnetic interaction
(Weiss temperature = +1 K) was detected in the case of (NH<sub>2</sub>−NH<sub>3</sub><sup>+</sup>)<sub>2</sub>([15]crown-5)<sub>3</sub>[Ni(dmit)<sub>2</sub>]<sub>6</sub>. The (NH<sub>2</sub>−NH<sub>3</sub><sup>+</sup>)<sub>0.8</sub>([18]crown-6)[Ni(dmit)<sub>2</sub>]<sub>2</sub> and (NH<sub>4</sub><sup>+</sup>)<sub>0.76</sub>([18]crown-6)[Ni(dmit)<sub>2</sub>]<sub>2</sub> crystals were isomorphous. The large
and flexible [18]crown-6 allowed for maintaining the same ionic channel structure through replacement of
the NH<sub>4</sub><sup>+</sup> cation by NH<sub>2</sub>−NH<sub>3</sub><sup>+</sup>.